Fast-setting, fibrous, portland cement-based building material

ABSTRACT

A fast-setting, fibrous, Portland Cement-based building material is made by soaking wood chips in water to provide substantially saturated wood chips, combining the saturated wood chips with a slurry of Portland cement to provide a wood chip/cement slurry, mixing a slurry of monomagnesium phosphate (“MOP”) with the wood chip/cement slurry to provide a quick-setting MOP/wood chip/cement composition, and compressing the quick-setting MOP/wood chip/cement composition to make the fast-setting, fibrous, Portland Cement-based building material. The inventive composition combines the best properties of cement and wood, yet uses recycled materials to make an environmentally-friendly building material.

REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. Continuation patentapplication Ser. No. 11/811,359, filed on Jun. 8, 2007 which is aContinuation of U.S. Continuation patent application Ser. No.10/746,111, filed Dec. 24, 2003, which is a Continuation of Ser. No.10/192,213, filed Jul. 10, 2002, which is a Continuation patentapplication Ser. No. 09/767,167, filed Jan. 22, 2001, which claimsbenefit of U.S. Provisional Patent Application 60/177,766, filed Jan.24, 2000, all of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to building materials, and moreparticularly to an environmentally-friendly building material thatcombines the strength and durability of concrete, with the sawability,nailability, and screwability of wood.

BACKGROUND TO THE INVENTION

One challenge facing the world today is how to balance the demand fornew construction materials with environmental concerns caused by theextensive use of wood. To address that challenge, “green” buildingtechnologies are being developed that use renewable or recycledresources in place of traditional materials.

One aspect of these green building technologies is the avoidance of newwood or whole wood sheeting. As is known to the art, the manufacture ofwhole wood sheeting creates large amounts of waste as the whole tree isunder-utilized. Moreover, wood is flammable, making wood constructionless safe than its non-flammable alternatives.

One alternative to wood is concrete masonry products, such as concreteblocks or bricks. These products are generally fireproof, but aredifficult to use in many applications because they cannot easily besawed, and cannot easily accept nails or screws. Special water-cooledconcrete saws are normally required to cut concrete, and concreteanchors are generally needed to use nails or screws in concrete.

It can be seen from the above that a need exists for a new buildingmaterial that: (1) uses renewable or recycled raw materials; (2) isfireproof; (3) can be sawed with conventional saws; and (4) canaccommodate conventional nails and/or screws. The present inventionaddresses that need.

SUMMARY OF THE INVENTION

Briefly describing one aspect of the present invention, there isprovided a method for making a fast-setting, fibrous, Portlandcement-based building material. The material is preferably made by:

-   -   (a) combining absorbent fibers (preferably wood chips) with        water to provide substantially saturated fibers;    -   (b) combining the saturated fibers with an aqueous slurry of        Portland cement to provide a fiber/cement slurry;    -   (c) combining the fiber/cement slurry with an aqueous solution        of monomagnesium phosphate (“MOP”) and allowing the        fiber/cement/MOP mixture to begin reacting; and    -   (d) compressing the fiber/cement/MOP mixture as it “sets” to        provide a fibrous, Portland Cement-based building material.

One object of the present invention is to provide a superior buildingmaterial that combines the advantages of cement and wood.

Another object of the present invention is to make a superior buildingmaterial from cement and recycled wood.

Other objects and advantages will be apparent from the followingdescription.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purpose of providing a further understanding of the principlesof the invention, reference will now be made to preferred embodimentsand specific language will be used to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended. All alterations, modifications, andfurther applications of the principles of the invention, whetherpreferred or not, are intended to be within the scope of the inventionas broadly defined.

As indicated above, the present invention combines a water-absorbentfibrous material (such as wood chips) with Portland cement to make afiber/cement slurry, and then combines the fiber/cement slurry with afast-setting binding agent such as monomagnesium phosphate (“MOP”) tomake a cementitious material. The cementitious material can be used inessentially any way that other building materials, such as wood orcement blocks, are used. Building blocks and fence posts are among themost preferred commercial embodiments.

The invention finds particular advantage in its ability to use recycledor waste wood chips as the fiber material. In some less preferredembodiments, new or recycled paper may be used in addition to, or as areplacement for, the wood chips. Alternatively, other synthetic ornatural water-absorbent fillers may be used to supplement or replace thewood or paper fibers, although those embodiments are less preferred intesting to date. (For the remainder of this disclosure, wood chips willgenerally be used as the water-absorbent fiber material. It is to beunderstood though, that other fibers could be used as noted above.)

The wood chips or other water-absorbent fibrous material is preferablysized between “mulch”-sized chips and wood “shavings.” Most commonly, amajority of the wood chip material is provided by chips that are betweenabout 0.50″ and 1.50″ in length (12 to 38 mm), with chips between 0.50″and 1.0″ long being more preferred. Similarly, a substantial portion ofthe wood chip material is provided by chips that are between about0.125″ to 0.50″ thick (3 to 12 mm), with chips between 0.125″ and 0.25″thick being more preferred. Lastly, a substantial portion of the woodchip material is provided by chips that are between about 0.125″ to 1.0″wide (3 to 25 mm), with chips between 0.25″ and 0.50″ wide being morepreferred. Pieces within or near those size ranges are generally largeenough to provide structural integrity to the finished product, yetsmall enough to be held firmly in the cement/MOP matrix. The appropriatesize will depend somewhat on the fiber material being used, theconsistency of the cement and the MOP, and the end use for the finishedproduct.

Further as to wood chip size, while it is appreciated that the particlesmay be of various sizes, a substantial volume of the fibers should belarge enough to grip and/or hold a nail or screw when penetrated.Preferably, the pieces are large enough that at least 25% of the volumeof the chips can be compressed by 50% when penetrated by a nail orscrew, thus allowing for tight penetration. FIG. 1 shows a screwpenetrating the inventive material, with the wood chip material having asubstantial portion of pieces that are large enough to compress aroundand grip the screw.

Although in some embodiments dry fibers are used, in the most preferredembodiments the fibers are soaked in water before being added to thecement. It is believed that soaking fills the spaces in the fibers withwater, and allows the cement/MOP matrix to more easily enter and fillthose spaces. When pre-soaking is used, it should be for a timesufficient to substantially saturate the wood chips (or other fibers),with 50-100% saturation being preferred, 60-95% saturation being morepreferred, and 70-90% saturation being most preferred.

After soaking, the fibrous material is preferably drained to remove anyresidual water—particularly water that remains on the surface of thematerial. It is not necessary that the surface of the saturated materialbe dry, but it is preferred that the amount of water surrounding (asopposed to within) the fibrous material be minimized. Generally, it ispreferred that the wood chips or other fibers be wet, but not drippingwet. In certain embodiments though (and particularly when less water isused in the Portland cement slurry that is combined with the fibers)dripping wet fibers can be used.

While the wood chips or other fibers are soaking or draining thePortland cement slurry can be prepared. Generally, the Portland cementslurry is prepared by combining dry Portland cement with water at aratio of between about 1:1 to 4:1 (cement:water). In the most preferredembodiment a ratio of about 2:1 (cement:water) is used. The cementslurry is mixed until smooth, as is known to the art.

When the “saturated” fibers and the cement slurry are both ready, thetwo components are mixed together to make a wet cement/fiber mixture.Preferably, the ratio of wet fiber to wet cement in the cement/fibermixture is between about 1:2 and 1:4 (weight-to-weight), with 1:3 beingmost preferred. The components are mixed until the wood chips or otherfibers are well coated.

In an alternative embodiment the cement slurry is made by adding drycement and water to the saturated wood chips and mixing thoroughly tomake the cement/wood chip slurry. This embodiment eliminates the need toadd the wood chips to the cement slurry after the slurry is mixed.

As to the binding agent, monomagnesium phosphate (“MOP”) is mostpreferred in testing to date. The MOP is mixed with water, with a ratioof about 2:1 (MOP:water) being preferred for most applications. Inalternative applications MOP:water ratios may vary from 4:1 to about1:1.

When the MOP is initially combined with the water, the MOP particles donot immediately go into solution. Accordingly, the MOP and water arepreferably mixed for several minutes (preferably between about 20 and 40minutes) until the MOP and water combine to form a “creamy” solution. Itis this well-mixed MOP/water preparation that is combined with thecement/fiber slurry prepared above.

As previously indicated, the material of the present invention isprepared by mixing the MOP/water preparation with the cement/fiberslurry. The mixing serves to ensure that the components are fairlyevenly distributed, and proceeds until the MOP begins to “react” withthe fiber/cement slurry. The reaction is exothermic, so the mixing maybe stopped when the mixture begins to get warm and “set.”

The last step in the preparation of the inventive material is thecompression step. In this step the material is “pressed” with a force ofat least about 50 psi, most preferably in a mold to shape the product.In the most preferred embodiments the material is pressed using a forceof between about 200 and 2000 psi.

It is to be appreciated that the cementitious material is substantiallyfireproof, much as conventional cement is. It is also to be appreciatedthat the cementitious material has properties that are not possessed byconventional cement. For example, the cementitious material is sawable(can be sawed with a conventional saw), and nailable (can be nailed withconventional nails), much as wood is. Moreover, screws can be usedwithout the anchors required by conventional concrete.

Reference will now be made to specific examples using the processesdescribed above. It is to be understood that the examples are providedto more completely describe preferred embodiments, and that nolimitation to the scope of the invention is intended thereby.

EXAMPLE 1

A 4″ by 4″ by 1½″ block is prepared as follows. First, soak ½ lb. of“dry” wood chips in water overnight or until substantially saturated.Then, drain the excess water from the mixture. In a separate container,combine 1 lb. dry Portland cement with ½ lb. water. Mix to make a cementslurry. Add the wet fibers to the cement slurry and mix thoroughly untilall the particles of the fiber are coated with the slurry. The mixturewill feel sticky, and you will not feel any grain.

While the fiber/cement slurry is mixing, combine ¼ lb. monomagnesiumphosphate (“MOP”) with ⅛ lb. water. Mix gently for 20-30 minutes, oruntil the MOP starts to feel warm. The consistency of the MOP mixturewill also become thick and creamy.

When the MOP has reacted with the water to become warm, add it to thefiber/cement slurry. Mix quickly and thoroughly, and place in a mold ifa specific shape is desired. The mixture will start to harden quickly,and can be pressed into desired shapes and/or dimensions duringhardening.

EXAMPLE 2

A 4″ by 4″ by 1½″ block is prepared as follows. First, soak ½ lb. ofrecycled paperboard and/or cardboard (cut into small pieces the size ofwood chips) in water overnight or until substantially saturated. Then,drain the excess water from the mixture. In a separate container,combine 1 lb. dry Portland cement with ½ lb. water. Mix to make a cementslurry. Add the wet fibers to the cement slurry and mix thoroughly untilall the particles of the fiber are coated with the slurry. The mixturewill feel sticky, and you will not feel any grain.

While the fiber/cement slurry is mixing, combine ¼ lb. monomagnesiumphosphate (“MOP”) with ⅛ lb. water. Mix gently for 20-30 minutes, oruntil the MOP starts to feel warm. The consistency of the MOP mixturewill also become thick and creamy.

When the MOP has reacted with the water to become warm, add it to thefiber/cement slurry. Mix quickly and thoroughly, and place in a mold ifa specific shape is desired. The mixture will start to harden quickly,and can be pressed into desired shapes and/or dimensions duringhardening.

While the invention has been illustrated and described in detail in theforegoing description, the same is to be considered as illustrative andnot restrictive in character, it being understood that only thepreferred embodiments have been shown and described, and that allchanges and modifications that come within the spirit of the inventionare desired to be protected.

1. A method for making a cementitious material, said method comprising:(a) combining absorbent fibers with water to provide substantiallysaturated fibers; (b) combining said substantially saturated fibers withan aqueous slurry of Portland cement to provide a fiber/cement slurry;(c) providing an aqueous mixture of monomagnesium phosphate (MOP) andwater, wherein the ratio of MOP to water is about 2:1 (d) combining thefiber/Portland cement slurry with said aqueous mixture of monomagnesiumphosphate and water and allowing the fiber/cement/MOP mixture to beginreacting; and (e) compressing the fiber/cement/MOP mixture before itfinishes “setting” to provide a fibrous, Portland cement-based buildingmaterial.
 2. A fast-setting, fibrous, Portland cement-based buildingmaterial comprising substantially saturated absorbent fibers dispersedthroughout a mixture comprising an aqueous slurry of Portland cement andan aqueous solution of monomagnesium phosphate.
 3. A fibrous, Portlandcement-based building material comprising absorbent fibers fixed in aset matrix of Portland cement and monomagnesium phosphate.